The preset invention relates to a throttle valve device used for controlling an intake air quantity of an automotive engine, and especially, to a throttle valve device for driving the throttle valve to open/close by an electric motor.
Heretofore, a throttle valve device of an automotive engine comprising a throttle body, a throttle valve rotatably supported by the throttle body, and an electric motor for rotating the throttle valve has been known (refer for example to Japanese Unexamined Patent Publication Nos. 9-287485 and 11-210501).
In a vehicle utilizing such a throttle valve device, a control unit for controlling the engine, which is provided separately from the throttle valve device, installs therein a drive circuit for driving the electric motor. In general, the engine control unit of the engine directly controls the electric motor.
As for the electric motor equipped in the throttle valve device, either a direct-current motor or an alternating-current motor is used according to the condition of use. Further, since required output torque differs according to the displacement of the engine or the bore size of the intake passage, different types of electric motors are used corresponding to different types of vehicles.
According to the prior art, there is a need to change the specifications of the drive circuit installed in the control unit for controlling the engine corresponding to the change of electric motor, and many types of control units having different specifications corresponding to various types of electric motors must be prepared, causing a problem of increase of the manufacturing cost, and reduction of the productivity.
The present invention aims at solving the above mentioned problems in the prior art. The object of the invention is to provide a throttle valve device of an engine capable of easily managing the combination of an electric motor and a drive circuit which are in a compatible relation, without having to prepare many kinds of control units in order to correspond to the change in specification of the electric motor.
In order to achieve the above object, the present invention is constituted such that a motor drive circuit is mounted to a throttle body separately from a control unit.
According to this constitution, the drive circuit compatible with the electric motor used in the throttle valve device is mounted to the throttle body, while the separately mounted control unit controls the electric motor via the drive circuit. Accordingly, even when drive circuits having different specifications are needed for various types of electric motors, the control unit can be standardized. Moreover, the combination of the electric motor and the drive circuit is fixed for every throttle body, to thereby easily manage the combination of the electric motor and the drive circuit.
The motor drive circuit may be cooled with the cooling water (i.e., a cooling liquid) of the engine.
According to this constitution, even when elements constituting the motor drive circuit, such as transistors, generate heat, heat radiation is accelerated by using the cooling water of the engine thereby improving the durability and reliability of the motor drive circuit.
Even further, a circuit case may be formed integrally to the periphery of the throttle body for accommodating the motor drive circuit therein.
According to this constitution, the motor drive circuit can be easily mounted to the throttle body while reducing the number of parts.
Moreover, when forming the circuit case integrally to the periphery of the throttle body, a connector may be provided to the circuit case for connecting the motor drive circuit to the control unit (peripheral device) and to the electric motor.
According to this constitution, the motor drive circuit can be easily and reliably connected to the motor drive circuit and to the electric motor.
These and other objects and aspects of the present invention will become apparent from the following description on the preferred embodiments of the invention with reference to the accompanied drawings.
The other objects and features of this invention will become understood from the following description with reference to the accompanying drawings.